captioning sponsored by macneil/lehrer productions >> woodruff: student loan debt keeps climbing, two-thirds of last year's college graduates owe an average of more than $26,000. good evening, i'm judy woodruff. >> warner: and i'm margaret warner. on the "newshour" tonight, we get the latest on the college debt burden and examine what the presidential candidates plan to do about it. >> woodruff: then, we look at the stepped-up cyber attacks on u.s. banks by iranian hackers.